High temperature strain gauges are precision sensors for measuring the strain of hot end components in aeroengines, and the structure of their sensitive grids directly affects the measurement accuracy and fatigue life. To reduce the measurement error of high temperature strain gauges and improve their fatigue life, a structural parameter optimization method and a fatigue life reliability assessment method are proposed. Firstly, the length, spacing and number of bends of the sensitive grid are taken as optimization variables, and the measurement error and fatigue life are taken as optimization objectives to establish a multi-objective optimization model. The multi-objective grey wolf optimization algorithm (MOGWO) is used for iterative optimization and solution. Based on the optimized structural parameter combination, high temperature strain gauge samples were prepared and vibration fatigue tests were conducted at 1 000℃ to obtain effective fatigue life data, verifying the effectiveness of the optimization method. In view of the small sample size, dispersion and right skewed distribution of the test data caused by the dispersion of material properties and manufacturing errors, a set of small sample fatigue life reliability analysis methods suitable for high temperature strain gauges is proposed. To compare the fitting performance of normal distribution, lognormal distribution and three-parameter Weibull distribution, the K-S test method and regression test method are combined to determine that the three-parameter Weibull distribution has the highest fitting degree for the test data. Then, the Bootstrap method is used to estimate the confidence intervals of the parameters of the three-parameter Weibull distribution, and the quantitative relationship between reliability and fatigue life is finally established. The results show that the measurement error of the optimized sensitive grid structure is reduced by 5.3%, and the fatigue life is increased by 22.4%. The research results provide a comprehensive theoretical method and experimental basis for the design and life reliability assessment of strain gauges in high temperature environments.